This invention relates to engine mounts for jet aircraft engines and more particularly relates to an aft engine mount that provides adequate support for the engine and accommodates thermal growth of the engine and also includes vibration isolation.
Typically, a jet engine is mounted beneath the wing of a commercial airliner by forward and aft engine mounts attached to struts affixed to and extending downwardly from the wing structure. The forward mount is typically rigid and thermal expansion of the engine, both radially and longitudinally, is accounted for in the aft engine mount. The aft engine mount is also typically designed to react against vertical, side, and engine seizure (torque) loads. The problem of vibration isolation has not been adequately addressed by present engine mounts, although the use of vibration isolators to dampen airplane interior cabin rumble noise generated by the engine rotor and transmitted through the engine mount to the aircraft are basic requirements for many airplane models.
It has been difficult to design an aft engine mount with vibration isolators to react against engine torque because of the elevated temperature environment and because of the space limitations between the engine case and the strut lower surface. In most airplanes having wing-mounted engines, there is a need to install the engine as close to the wing as possible in order to obtain the maximum ground clearance and to shorten landing gear length for weight saving. Typically, the strut between wing and engine is reduced in height in order to allow a reduction in the space between the wing lower surface and the exterior contour of the engine cowling. However, airplane flutter may occur because of the "soft" structure of the strut, the softness of the strut structure being directly related to its short length or "shallowness."
It is therefore an object of the present invention to provide an aft engine mount with the capability of reacting against torque loads while substantially isolating the strut from engine vibration.
It is another object of this invention to provide such an aft engine mount that will fit into a minimum space between the wing and engine while permitting the maximum vertical dimension of the strut.
It is a further object of this invention to provide such an aft engine mount that also meets the usual requirements of load handling and is stiff enough to react against the vertical, side and torque loads, and also complies with existing standards for ease of manufacture, installation, and maintenance, and also that allows for the radial and longitudinal thermal growth of the engine.